RegisCA

End-of-session environment hygiene for the ggltcg repo. Run this to safely close out a working session: confirm no background subagents are still running, get back onto an up-to-date `main`, prune branches whose PRs have merged, and reset the `gh` account to RegisCA. Use whenever the user signals they're wrapping up — "let's wrap up", "end the session", "clean up before I go", "back to main", "we're done for today" — or asks to tidy the environment for the next session. This is environment cleanup ONLY; it deliberately does not write memories or update handoff docs (do those separately, they need judgment).